Governing mechanism for turbines.



PATBNTBDJULY 2s, 1907.

W. L. R. EMMET.

G QVERNING MECHANISM I EOR TURBINES.

APPLICATION FILED MAB. 17, 1908.

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"UNITED STATES PATENT oEEIoE.

WILLIAM L. R. EMMET,VOF SCHENECTADY, NEW-YORK, ASSIGNOIN TO GNERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

GOVERNING MECHANISM FOR TURBINES.

Specification of Letters Patent.

Patented July 23, 1907.

Application tiled March 17,1906. Serial No. 306,503.

To all whom it 'may concern:

Be it known that I, WILLIAM L. R. EMMET, a citizen The object of the invention is to improve the con-A struction and operation of such mechanisms.

For an understanding of the scope and nature of my improvements, attention is directed to the accompanying description and claims appended thereto.

In the accompanying drawings, which illustrate one of the embodiments of my invention, Figure l is a partial side elevation of a turbine fitted with my improved governing mechanism; Fig. 2 is an end view thereof;

Fig. 3 is a View in elevation of the valve-actuatingmechanism with the casing therefor in section; Fig. 4 is a plan View of the same with the cover of the casing removed; Fig. 5 is a cross section of the valve-actuating mechanism; Fig. G is a perspective view of the cross- A head and the valve actuators carried thereby; Fig. 7 is a perspective view of the mechanism used to shift the dogs which actuate the valves; Fig. 8 is a longitudinal: section oi the speedor load-responsive device; and Fig. 9 is a perspective view of oneof the valve-actuating dogs.

The invention is shown as applied to a multi-stage turbine of the Curtis type, but it is applicable to other types of turbines, as will be readily understood.

I have shown the mechanism in connection with admission valves only, but it can be used for operating the valves between stages, or for operating both the admission and stage valves. It is applicable also to singlestage turbines.

l represents the turbine with the rst-stag'e partly in section to show one of the admission nozzles 2, which may be of the expanding or non-expanding type, 3 the wheel buckets and 4 the intermediate or stationaryA buckets, where such buckets are required, as rfor example, where the velocity of the steam or other motive Huid is abstracted by two or more operations in the same embodiment illustrated a plurality of these valves is provided, but in its simplest form I may use only a single valve.

The rotary memberof the turbine is mounted on a shaft 6 carried by suitable bearings 7, of which one is shown. On the end of the shaft is a speed-responsive device incl'osed by a casing 8. The said device imparts movement to the means controlling the opening and closing of the valves byahorizontal lever 9 attached to a connecting rod l0, the latter being pivotally united to an arm 1l mounted on the upright spindle 12. On the upper end of the spindle is an arm 13, Figs. l and 2, connected to a horizontally disposed lever 14 pivoted at a point between its ends to the casing l5 that incloses the actuating mechanism. As the speed changes the upright spindle is rocked to and fro, causing the dogs to engage or let go of the valve stems or attached crossheads, as will appear later. The casing is suitably supported, as for exampleby the posts or columns 16 attached to one'oi the main bearings.

The governing mechanism includes a vibrating lever 17l that is constantly in motion and which supplies the necessary power to open and close 'the valves one after the other or Ain any predetermined order. Motion is imparted to this lever by a vertically disposed connecting rod 18 receiving motion from a crank-pin 19, shown in dotted lines, Fig. 1. The pin is mounted on a disk 20 driven by the worm wheel 21 meshing with a worm 22 on the main shaft. This relation of parts insures continuous vibratory action of the lever 17 when the machine is in operation, and also a practically unlimited amount of power. It is preferable to reduce the speed of the parts by gearing where the turbine runs at the speeds commonly employed. The crank disk 20 also furnishes the power for driving the plunger 23 of the lubricating pump 24, the latter being inclosed in a Acasing 25 supported by the base of the turbine. By locating these parts between the bearing and the turbine proper, they are out oi the way end also leduce the longitudinal dimension of the machine. Connected with the pump is a chamber 26 to reduce the pulsating effect of the plunger on the discharged lubricant. Fluid from the pump is discharged by the pipe 27 into the pipe 28 located in the base of the machine. This pipe extends longitudinally through one side of the base,

then crosses over to the opposite side and extends parallel to the first portion back to the left-hand end of the machine. Lubricant under pressure is admitted to the left-hand bearing by the pipe 29, a similar pipe being provided for the other bearing. In this pipe is a valve 30 for regulating and shutting off the supply. The exhaust lubricant is returned from the bear-ing to the chambered casing inclosng the pump by the' pipe `31g?Between the pump and the air chamber" 26 is a check-valve 32 (Fig. 2) opening toward the-chamber. On the discharge side of the pump is an adjustable relief valve 33 by means of which the discharge pressure can be regulated. The casing 25 is normally filled with lubricant at atmospheric pressure, and the pump cylinder is lled by gravity through the opening 34, Fig. 1. casing is lubricated by an oil cup 35 located on the cover, and lubricant is returned to the system by the pipe 36 connected to a chamber in the bearing. The upper end of the pipe extends a certain distance into the casing so as to maintain a body of lubricant therein sufficient to lubricate the lower members. The arrangements of the ducts for lubricating the parts of the valveactuating mechanism will be described later. I

I have chosen as an illustration of my invention a mechanism having five admission valves, but the number can be increased or decreased as desired. Since all of the valves are alike, the description will first be directed specifically to one of them, and later to the means whereby the successive operation is attained.

Each valve is provided with a stem which is made in two parts 40 and 41,' so that the actuating mechanism can be removed from the valve proper. Between the two parts of the stem is a coupling 42. The portion of.

the stem directly attached to the valve is provided with an enlarged head which enters a head 43 on the other portion, the said head containing a downwardly opening slot 44, Fig. 6, through which the stem can be slipped. By means of this arrangement the outer portion of the stem can be' lifted bodily without 'disturbing the valve and its attached stem.

Extending longitudinally of the casing 15 is a main rock-shaft 45 and an auxiliary rock-shaft 46. The former is rigidly attached to the vibrating lever 17 which is kept constantly in motion by the crank 19,

Fig. 1. Motion from the main to the auxiliary r0ck.

shaft is transmitted by the connecting-rod 47 located at the far end of the casing 15, Fig. 5. This rod con nects the cranks 48 keyed or otherwise secured to the shafts. Mounted on and guided by these two shafts and arranged to slide longitudinally thereof as the speed of the tu'rbine changes, is a slide 49, Fig. 7, supported at four points and having projections 50 and 51 thereon to control the action of the double-ended dog 52 on the valve stem. The object in using an auxiliary rock-shaft is to overcome the static friction or friction of repose of the parts. I regard it as being a highly desirable arrangement because it reduces the load on the shaft governor at starting and aiso increases its effectiveness, but under certain condition I may substitute therefor a non-moving guide.

Mounted in suitable fixed guides 53 and 54 in the casing and arranged to move constantly to-and-fro is a cross-head 55 carrying the dogs 52, Figs. 5 and 9. Reciprocating motion is constantly imparted to the crosshead 55 from the rock-shaft 45 by means of the cranks 56 secured at opposite ends of the rock-shaft, and connecting rods 57 and 58. The obj ect in using two cranks and connecting-rods is to transmit motion and prevent binding of the parts. In certain cases, however, it is possible to use only one crank and connecting rod and locate them in a central position. The outer portion 41 of the valve stem passes through the casing 15 and is located in guides in the cross-head, the latter being The valve-actuating mechanism within the capable of; moving ltoangl fro without disturbing it. To prevent the stem from turning and thus gettin the actuating shoulders and the slot 44 in the couplir in other than a downward position, a pin 59, Fig. 5, mounted in the vcross-head and arranged to move in slot in the valve stern.

The dog 52 is pivoted centrally and has two working surfaces at opposite ends adapted to engage the shoulders 60 and 61 on the under side of the valve stem. It normally stands with one corner up and the other down; it has no intermediate or central position. To insure this action taking place, extension springs 62 are provided which work over a dead center. In order to obtain an effective snap action with a minimum height of parts, the dog is provided on its under side with a projection through which the pin 63 passes.

Ifo this pin are pivotally connected flat pieces 64 each having an enlarged hole to pass around the pivot of the dog, the upper end of each piece being connected to a tension spring 62. Other means can be employed to obtain this snap-like action of the dog Without departing from the spirit of my invention.

`The slide or means 49 controlling the action of the projections 50 and 51 on the pivoted dog 52 is connected by the flat rod 65 with the lever 14 pivotally supported on the outside of the casing 15. As the speed increases, the slide with its attached projections is moved outwardly thus causing the projection 51 to move under the incline surface at the end of the dog 52 at some portion of its stroke and raise the right-hand end,-thus permitting the next stroke of the cross-head 55 to the right to close the valve. Assuming that the load increases and the speed falls slightly, the reverse operation takes place, and the projection 50 moves under the left-hand end of the dog 52 and raises it a certain amount. and thev spring 62 snaps the dog into the position shown in Fig. 5, and the next outward stroke oi the cross-head 55 opens a valve.

The projections 5.() and 51 may be separated in the plane of the dog by a distance which is slightly greater than the Width of the dog measured in a plane at right angles to its length. In this event the dog can, at a definite speed of the turbine move to and iro without changing its position or the position of the valve. On the other hand, the projections may be so set that the distance between them, vmeasured in the plane of the dog, is less than the width of the dog, in which case the valve at the critical point in the regulation will, for a certain limited range of speed, open and close once for each strokeV of the cross-head.

Owing to the fact that there are a number of joints in the connection between the speed governor and the slide 49, containing more or less play, especially as the parts become worn, it is desirable to compensate therefor and eliminate the effect of said looseness as much as possible. To do this a spring 66, shown in dotted lines, Fig. l3, is attached to the slide 49, and to a iixed abutment 67 on the casing 15. The spring should be of such a length and character as to exert a substantially uniform tension on the slide irrespective of its position. Other means for accomplishing this can be provided.

. It now .remains to describe how the successive action of the valves both in opening and closing is accomplished. On the upper side of the slide are as many pairs of dog-controlling projections as there are valve if n e. f v v i f Y i I i row will act on the dogs one after the other and permit the cross-head to close the valves successively. The relation oi the rows of projections to the dogs is best shown in planin Fig. 4. The differencein position of two pairs Iof projections and their coperating dogs will best be seen by looking at the dogs at opposite ends of the slide. Under normal conditions certain of the valves will be closed, certain of them open, and at least one valve will be opening and closing frequently to admit pulsations of steam or other motive fluid from the valve chest to the fluid-discharging nozzle or other device. It will readily be understood that a given number of open nozzles will seldom exactly satisfy the load conditions, while a number greater by one than said number will supply too much, hence one valve will act as described and in so doing admit fluid in pulsations to the turbine.

As a refinement of the invention, the dogs and projections may be so related that the valve at the critical point in the regulation will open and close once for each stroke of the vibrating lever 17. This means that the distance between the dogs of a pair, measured in par-v allel planes extending longitudinally of a dog, is less than the width of a. dog.

Referring to Fig.l 8, 67 and 68 representthe weights of the speed governor each of which is provided with a hardened steel plate 69 having inner and outer shouldered portions adapted to receive the hardened knife edges 70 and 7l. The knife edges 70 are carried by links 72, the opposite ends of which are pivotally united to ythe movable abutment 73. Secured to the abutment by a bolt is a nut 74 having an external thread arranged to receive and retain one end of the weightopposing spring 75. The inner end of the spring is similarly provided with an externally threaded nut 77. The nut is also interiorly threaded to receive the adjusting bolt 78. The bolt is seated in a shell 79, that is removably secured in th'e recessed end of the bucket i wheel shaft 80. The shell isretained by a nut 81 to by a link 86. The lever is pivotally supported in anV openwork frame 87 that is bolted to the end of the bearing 7. The lever 9 is guided in its movements by a guide 88 on its under side.

With a valve gear of this character it is important to keep the parts well lubricated. With this end in view the oil cup 35 is mounted on the removable cover of the casing l5 and the lubricant therefrom drips into the tray formed in the upper side of the cross-head 55. In the tray are small oil-carrying passages 90 leading to the guides in the cross-head for the stems 41. The excess lubricant flows over the surface -of the stem and lubricates the upper surface of the dogs 52 and also the pivot 91 therefor, which in the present instance is common to all of the dogs. Passages 92 are also provided to lubricate the connecting-rods 57 and 58 and the attached cranks. As previously stated, the drain-pipe 36 leading from the casing l5 to the bearing 7 projects into the former by an amount sut'ricient to maintain a body of oil at about the level of the axis oi the main rock-shaft; this will abundantly lubricate the remaining elements, especially as the movements ofthe cross-head will tend to agitate the oil more or less. A

One of the very important features ot a valve gear is to arrange the parts so that they are readily accessible;

this has been done with the constructionshown. The valves are located in a chest that is detachably secured to the turbine and the actuators therefor in a casing supported by the bearing and having a removable cover to expose the parts. The cross-head is arranged to move bodily toward and away from the turbine with a defi- 4 nite number of strokes per minute, while the slide 49 carrying the projections governing the action ofthe dogs 52 is free to move to and fro in a longitudinal direction under the control of the speed governor, the direction of motion of the slide being at right'angles to that of the cross-head 55. When it is desired for any reason to take down the mechanism, the cover of the casing 15 is removed, thus exposing the cross-head. The screws for the cross-head guides 53 and 54 are removed, the connection broken between the rod 65 and the speed-actuated mechanism, and the pivots connecting the crossheads and the connecting-rods 57 and 58. The crosshead can then be raised to disengage the parts oi the valve stem and then moved longitudinally to withdraw the bar or rod 65. This exposes all of the dogs and the adjacent parts. The slide 49 can then be removed by raising it bodily. The remainder of the mechanism will then be accessible, as readily understood.

lIn accordance with the provisions ofrthe patent statutes, I have described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown .is only illustrative and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In a governing mechanism, the combination of a valve, a cross-head which is constantly reciprocated in a given path for opening and closing the valve, a means moving in a plane at an angie to the direction of motion of the cross-head for controlling the action thereof on the valve, and a device responsive to load changes for shifting said means.

2. In a governing mechanism, the combination of a valve, a cross-head which is reciprocated in a given path, a dog carried by the cross`head for opening and closing the valve, a means moving in a plane at right-angles`to the direction of motion of the cross-head for moving the dog in a manner to cause it to operate the valve, and a load-responsive device for shifting the said means.

3. In a governing mechanism, the combination of a valve, a means which ls reciprocated in a given path, a double-acting pivoted dog carried by the means for operating the valve, a device for snapping the dog first into one of its positions and then the other, and a means responsive to load variations for controlling the action of the dog.

4. In a governing mechanism: the combination of a valve, a means Which is reciprocated in a given path, a

double-acting pivoted dog carried by the means for operating the valve, a spring working over a dead center for snapping the dog first into one of its positions and then the other, and a speed-responsive device for tilting the dog in one direction or the other as the load conditions change.

5. In a governing mechanism, the combination of a valve, an actuator, a double-ended pivoted dog carried by the actuator adapted to engage the valve stem and move it, a slide for causing one end or the other of the dog to engage the stem, and a speed-responsive device for moving the slide.

6. In a governing mechanism, the combination of a valve having a stem, a cross-head through which the stem freely passes, a means for reciprocating the cross-head without moving the valve, a dog carried by the cross-head which is adapted to engage with and move the valve, and pins moving in response to speed changes for causing the dog to actuate the valve.

7. In a governing mechanism, the combination of a valve having a stem, a cross-head, a guide therefor, a rockshaft, a connection between the rock-shaft and the crosshead for transmitting motion, a valve stem, and a means carried by the vcross-head and acti-ng in response to load changes for opening and closing the valve.

8. In a governing mechanism, the combination of Aa valve having a stem, a cross-head, a guide therefor, a means for transmitting motion from the cross-head to the valve, a slide moving at an angle t'o the path of movement of the cross-head, a guide therefor, a device carried by the slide for controlling the said means, and a speed-responsive device connected to and moving the slide.

9.' In a governing mechanism, the combination of a valve, a means for opening and closing the valve, a device for controlling the action of the said means in response to load changes, and a support for the said device which is normally in motion to prevent the friction of repose.

10. In a governing mechanism, the combination of a valve, a means for openingand closing the valve, a devicev for controlling the action of the said means in. response to load changes, a guide for said device having parallel surfaces, and means for keeping the guide in motion to prevent the friction of repose.

11. In a governing mechanism, the combination of a valve, a means for opening and closing the valve, a device for controlling the action of the said means in response 'to load changes, a pair of connected rock-shafts which form a guide for the said device, and a driving means for rocking the shafts.

12. In a governing mechanism, the combination of a valve, a means for opening and closing it, a device governing the action of said means, a speed governor connected to the device, and a means for taking up the play of the parts.

13. In a governing mechanism, the combination of a valve, a means for opening and closing it, a device governing the action of said means, a speed governor connected to the device, and a spring for taking up the play in the connection between the governor and said device.

14. In a governing mechanism, `the combination of a plurality of valves, a cross-head which is common thereto means carried by the cross-head f or actuating the valves, a slide arranged to lmovel to and fro at right angles to the plane of movement of the cross-head in response to load changes, and pins or projections on the slide for controlling the action of said means.I

l5. In a governing mechanism, the combination of a plurality of valves, a cross-head which is common thereto, 'means carried by the cross-head for actuating the valves, a slide arranged to move to and 'fro at right angles to the plane of movement of the cross-head in response to load changes, and pins or projections on the slide arranged in sets to cause the said means to open and close the valves successively.

16. In a governing mechanism, 4the combination of a plurality of' valves, a cross-head, a rock-shaft, cranks and rods driven by the shaft and connected to opposite ends cross-head for actuating the valves, a slide arranged to i move at right angles to the plane of movement of the cross-head, means on-the slide for controlling the dogs,'

and aspeed-responsive device connected to and moving the slide.

18. `In a governing mechanism, the combination of a valve, a two-part stem therefor, a. coupling between the parts of the stem, a reciprocating cross-head, a means carried by the cross-head which acts through one part of the stem to open and close the valve, and a speed-responsive device controlling the action of said means.

19, In a governing mechanism, the combination of a casing, located in the casing, and dogs mounted on and removable with the cross-head for actuating the valves.

20. In a governing mechanism, the combination of a casing, a plurality of valves,'a double-acting dog for actu ating each of the valves, a springfor causing each dog to snap from one position to anothera'nd a removable crosshead locatcdvin the casing to v e dogs and springs are attached and removable thel itlx 21. In .a govern-ing lvnechanism, 'the'combination of a casing, a plurality of- .valve actuators therefor, a .crosshead for moving the aetuato ,and a receptacle or tray in the cross-head for supplying lubricant to the actuators.

22. In a governing mechanism, the combination of a cross-head, a plurality of valves, actuators therefor car ried by the cross-head, a slide arranged to moveto and fro, and a four-point support for the slide.

23. In a governing mechanism, the combination of a regulator, a tilting dog that moves to and fro and when in one position moves the regulator in one direction and when in the other of its positions moves the regulator in the opposite direction, and a governor for controlling the action ofthe dog.

24. In a governing mechanism the combination of a plurality of regulators, a plurality of dogs for moving the regulators 'in one direction or the other, a sliding cross-head forming a support common to dogs, and a governor for controlling the dogs.

25. In a governing mechanism, the combination of a valve, a stem therefor having shoulders, a tilting dog pivotally supported at one side of and at a point between the shoulders, a means forA moving the pivot of the dog to and fro, and a device responsive to load changes for causing one end of the dog or the other to engage a shoulder on the stem and move the valve.

26. In a governing mechanism, the combination of a valve, a stem therefor having opposing shoulders, a guide for the stem, a means for preventing the stem from turn-v ing, a double acting tilting dog situated on the side of the stem adjacent the shoulders, an actuator for the dog, and a governor for controlling the action of the dog on tho shoulders.

In witness whereof I have hereunto set my hand'this 16th day of March, 1906.

WILLIAM L. R. EMMET.

Witnesses:

BENJAMIN B HULL, HELEN OnFonD. 

